Television-based entertainment systems are expanding the programming and services that they offer. In addition to television program content such as that found on broadcast and traditional cable networks, television service providers are adding interactive services, features, and applications. Such content and additional information are downloaded over a television-based network for display, use, and/or storage on client-side set-top boxes or similar devices. These downloads include audio and/or video information that are transmitted in real-time. To reduce the amount of data that is streamed, the information is typically compressed from a first size to a second smaller size. Because the streaming occurs in real-time, the information flow is compressed on-the-fly without knowing the ultimate data rate level and/or amount of data that will be produced and therefore streamed.
Regardless of whether the information to be transmitted is intended to be sent over a network or stored in a memory (or both), there is a finite amount of bandwidth available for the compressed data. For example, a given network has a maximum transmission capacity at which it is designed to operate, often on both an individual user level and on a total composite level. Audio and video information may be compressed by encoding it using any of many available approaches and standards, such as a Moving Pictures Expert Group(MPEG)-based standard. The encoding reduces the bandwidth needed to transmit or store the resulting data. However, the degree to which encoding compresses information varies depending on the information itself. For example, some information compresses to one-fourth of its previous size while other information compresses to only one-half of its previous size, even using the same encoding parameters.
A transmission or storage medium's bandwidth limit(s) provide a guide as to what encoding parameters should be selected for compressing audio and video information to achieve a desired data rate that meets the medium's bandwidth limits. Unfortunately, because the same encoding parameters compress different information to differing degrees, it can be difficult if not impossible to accurately predict the ultimate bandwidth limits that will be met using a given set of encoding parameters on a real-time information flow.
In fact, there are two primary options for selecting encoding parameters in concert with adhering to bandwidth limits of a given transmission or storage medium. First, aggressive encoding parameters may be selected to significantly reduce the size of the resulting compressed data stream to ensure that any bandwidth limits are satisfied, but presentation quality suffers when the overly-compressed data is decompressed and the original audio and video information is presented. Second, conservative encoding parameters may be selected so that both compression and consequential quality reductions are minimized, but then data may be dropped or otherwise lost if medium bandwidth limits are exceeded. For example, if the memory storage bandwidth limit is exceeded prior to completion of a real-time data streaming event, then any un-stored data is lost.
Accordingly, for television-based entertainment systems, there is a need for schemes and techniques to enable the real-time compression of audio and video information that will meet bandwidth constraints while not unduly reducing the resulting presentation quality of the audio and video information after decompression.